The present invention relates to diving masks as well as to a method for the manufacture thereof.
A diving mask comprises usually a face-piece having, formed therein, one or more openings for housing one or more lenses, a frame for fixing the lenses inside the face-piece and a strap for connecting the mask to the diver's head.
When manufacturing face-pieces for diving masks it has always been necessary to achieve a compromise between various requirements which often tend to conflict with each other.
So for instance, in a diving mask it is requested:    (a) that the rim of the mask which is in contact with the face of the scuba diver be as much as possible soft in order to ensure maximum comfort and sealing capacity;    (b) that the portion of the mask lying beneath the rigid frame, and in which are formed the openings housing the lenses, be formed with a certain structural solidity which may be achieved only with relatively more rigid materials, in order to avoid that, if too soft, this portion could be withdrawn from beneath the frame if subjected to a certain tensile stress for example when putting on the mask;    (c) that the portion of the mask covering the nose of the diver be as much as possible soft in order to facilitate the compensation manoeuvre by avoiding at the same time that the underlying rim portion be twisted, thus facilitating the infiltration of water in the mask.
While initially in this technical sector the most common material used for manufacture of the face-piece of the mask was without doubt natural rubber, nowadays the elastomers which are most widely used are silicones, fluorosilicones, fluoro hydrocarbon rubbers such as Viton™, neoprene, acrylonitrile-butadiene rubber and ethylene-propylene rubber. Of these, the elastomers which are most versatile in terms of their rigidity range are silicones, which may have a hardness of between 5 and 90 degrees Shore A (ISO 868). In addition to this, silicones have notable properties as regards chemical inertia and tolerance by the user, which make them even more suitable for this type of processing operation.
It remains a problem, however, that, despite notable progress achieved in relation to the materials during recent decades, the rigidity of the elastomer material used is today still the result of a compromise between the two opposing sets of requirements mentioned above.
From the prior art, and for instance from US-A1-2004/143889; U.S. Pat. No. 4,087,865; U.S. Pat. No. 6,253,387 B1 and US-A1-2005/120468 swim goggles are known obtained by the combination of two different compositions of materials having different hardness. However, in the swim goggles: (1) the portion covering the nose of the diver is missing, and therefore all problems mentioned before sub (c) are missing; and (2) since the swim goggles are formed by two distinct and disjoint eye pieces which are applied on the ocular orbits, also the problem of the peripheral seal mentioned sub (a) is missing.
The object of the present invention is therefore to provide a mask, the face-piece of which is able to satisfy fully both the needs of a structural nature and those relating to sealing capacity and comfort.
The present invention therefore relates to a diving mask comprising a face-piece having, formed therein, one or more openings for housing one or more lenses, means for fixing the lenses inside the face-piece and means for connecting the mask to the diver's head; said face-piece is formed by at least two portions, which are stably connected together, said two portions being respectively made using two materials which are different at least from the point of view of the rigidity, one of the two materials being more rigid than the other one.
Said materials are elastomer materials such as for example silicones, fluorosilicones, fluoro hydrocarbon rubbers, neoprene, acrylonitrile-butadiene rubber and ethylene-propylene rubber and, of these, silicones are preferred, in particular liquid silicone rubbers (LSR) having a hardness of between 10 and 70 degrees Shore A.
In one embodiment, the portions of the face-piece of the mask intended to come into direct contact with the diver's face are made with a softer material, while the other materials are made of more rigid material. The softer material will be an elastomer material with a hardness of between 10 and 40 Shore A, while the more rigid material will have a hardness of between 40 and 70 Shore A.
The materials chosen for the different portions may preferably belong to the same class of compounds so as to improve their chemical bonding capacity during assembly of the face-piece; alternatively, the various portions of the face-piece will be made so as to ensure an adequate mechanical union between them.
The present invention furthermore relates to a method for the manufacture of face-pieces for diving masks, comprising the formation of the face-piece as at least two portions, said portions being made using at least two different materials, preferably elastomers, having a varying rigidity. The face-mask may be made by means of injection-moulding and the different portions may be made by means of successive overmoulding of the softer portions onto the more rigid portions; alternatively, moulding may be performed by means of twin injection, forming the more rigid portions and the softer portions substantially at the same time.
By this method it is also possible to colour in different manners the two elastomeric compositions, in order to provide an individualising aspect to the thus obtained mask.